Lucid Lynx is the code name for Ubuntu 10.04, and its release is scheduled for in April 2010. There are now available Light (Radiance) and Dark (Ambiance) themes, you can install them on Ubuntu 9.04 “Karmic Koala, you should have installed the last Murrine environment to run them correctly. Obviously the new light themes are going to reflect Ubuntu’s brand and colors. Judging by this new theme Ubuntu clearly has had some inspiration from Mac OS X. Some theme elements might change until Ubuntu 10.04 Lucid will be released. Please note: these themes have just been released, so expect to find bugs.
Free Download:Ubuntu 10.04 themes